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Improved PCO2 measurement in six standard blood gas analysers using a phosphate-buffered solution for gastric tonometry.

Authors
  • Knichwitz, G
  • Mertes, N
  • Kuhmann, M
Type
Published Article
Journal
Anaesthesia
Publication Date
Jun 01, 1995
Volume
50
Issue
6
Pages
532–534
Identifiers
PMID: 7618670
Source
Medline
License
Unknown

Abstract

The measurement of gastric intramucosal pH serves as a non-invasive technique for early detection of gastrointestinal ischaemia in critically ill patients. The method is based on the determination of the partial pressure of carbon dioxide in a 0.9% saline solution using a standard blood gas analyser. However, the use of standard blood gas analysers leads to an underestimation of carbon dioxide partial pressure in saline. Instrumental biases of six blood gas analysers were investigated using either a saline or a phosphate-buffered solution. Both test solutions were equilibrated with five defined carbon dioxide concentrations. Each blood gas analyser underestimated this defined partial pressure of carbon dioxide with a bias between -3.7% and -57.5% if saline was used. The phosphate-buffered solution considerably improved instrumental precision, resulting in biases between +2.7% and -17.6% Thus, a phosphate-buffered solution increases the accuracy of gastric intramucosal pH measurement.

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